A collaboration between these two experimental doom metal bands, Altar also features Thrones' Joe Preston, Soundgarden guitarist Kim Thayil and members of Jesse Sykes and the Sweet Hereafter. The first song, "Etna," absolutely trudges with all the slo-metal crush of a glacier boring out of the Grand Canyon millions of years ago. All six cuts find both Boris and Sunn O))) meeting each other's potential, and it's great to hear Sunn O))) with drums. Thayil turns last song "Blood Swamp" into a drone metal version of Floyd's "Echoes."